Computer users are accustomed to using a mouse and keyboard as a way of interacting with a personal computer. While personal computers provide a number of advantages over written documents, most users continue to perform certain functions using printed paper. Some of these functions include reading and annotating written documents. In the case of annotations, the printed document assumes a greater significance because of the annotations placed on it by the user. One of the difficulties, however, with having a printed document with annotations is the later need to have the annotations entered back into the electronic form of the document. This requires the original user or another user to wade through the annotations and enter them into a personal computer. In some cases, a user will scan in the annotations and the original text, thereby creating a new document. These multiple steps make the interaction between the printed document and the electronic version of the document difficult to handle on a repeated basis. Further, scanned-in images are frequently non-modifiable. There may be no way to separate the annotations from the original text. This makes using the annotations difficult. Accordingly, an improved way of handling annotations is needed.
One image pattern is shown in FIG. 10. This pattern is used by the Anoto pen (by Anoto Inc.) to determine a location of a pen on a piece of paper. The pattern as shown in FIG. 10 is difficult to easily orient from any portion and determine the accurate rotation of the pattern. If the determination of the rotation is based on the decoding of the pattern itself to find information encoded in the data stream, this determination requires significant processing for decoding the data stream itself to determine the proper orientation of the pattern. This labor-intensive decoding approach impedes quick adoption of the pattern, as it requires substantial hardware resources just to locate a captured portion of the image. Scaling of the use of the pattern beyond a short note becomes difficult (for example, composing a large document by handwriting only) as each camera image relating to an ink stroke may need to be completely processed in all orientations to determine the proper orientation of the pattern. An improved pattern is needed to represent data streams.